The disclosure relates to a content addressable memory, and can be particularly applied to a content addressable memory that can be incorporated into a semiconductor device and a semiconductor device incorporating a content addressable memory.
A data word (entry) matching a search word (search data) is searched for among those stored in a storage device car led an associative memory or a CAM (Content Addressable Memory). In the case where the word data matching the search word can be found, the address thereof is output.
As the CAM, there are a BCAM (Binary CAM) and a TCAM (Ternary CAM). Each memory cell of the BCAM stores information of either “0” or “1”. On the other hand, each memory cell of the TCAM can store information of not only “0” and “1” but also “Don't Care”. The “Don't Care” indicates that either of “0” and “1” may be stored.
A TCAM device using the TCS has been widely used for address search and access control in a router for a network such as the Internet.
Japanese Unexamined Patent Application Publication No. 2006-236515 discloses a test technique of a CAM macro.